Method of killing submerged waterweeds



Patented June 17, 1952 METHOD OF EKILLIN G SUBMEBQGED';

.. TE ED John M-.- Shaw :and Thomas RzuBartley,-. Denver,

0010;, 'anmRichard- S.- Rosenfels, Richl and Wash.,-assignorsto the United .States of Amer;- ica as represented by the Se'cretary oi the.

iil 7 No 'Di awing. Application-Angusten;194a,; Serial No. 47,134

1.01am. (01. 71 m) (Granted under the: act of- March 3,. -1883-,;- as.

The invention described herein may be mann factured and used by or for the Government of the United States for governmental purposes without the payment to us of any royalty thereon in accordance with the provisions of the act of April 30, 1928 (Ch. 460, 45 Stat. L. 467).

The present invention relates to a herbicidal composition and a method for killing and controlling the growth of water-weeds in canals, ir-

rigation ditches, ponds, and like bodies of water;

The elimination of submersed waterweeds from irrigation ditches is a serious problem. Besides cutting down the capacity of irrigation canals, waterweedscause silt to be deposited which makes costly dredging necessary. Another toll taken by these weeds is loss of water through-increased evaporation and seepage. When the canal water level must be raised above normal in an attempt to increase'the flow of water which is retarded by waterweeds, erosion and breaks are common. Growths of waterweeds clogs drains, cause them to function poorly, maykeep potentially good land waterlogged, and often increase alkaline deposits-in the soil. Heretofore, methods for the removal and control of waterweeds havebeen both expensive and laborious.

Accordingly, it is-an object of thisinventicn to provide a cheap herbicidal composition'forcon-- trolling. the growth of wate rweeds and a simple 7 method for the applicationof such compositions;

Other objects and advantages-will beapparent or will appearhereinafterr These .objects and advantages are accomplished inaccordance with the present invention of the method for filling submersed waterweeds growing in a body of water which comprises the pressurized introduction of a fin ely divided herbicidal agent beneath the surface of the water body in which the waterweeds to be eliminated are growing, said herbicidal agent being comprised of a mixture of aromatic hydrocarbons havingv a boiling pointrange lyingybe-e tweenabout 250 to 450 .degreessFahrenheit and an emulsifying. agent.

Suitable aromatic hydrocarbons for purposes:-

of this invention include those distillate fractions of coal tar or petroleum origin which are composed of the higher homologues of benzene and of which not less than about 10 percent have.

zene, .tri-methyl benzene, methyl .propyl .benzene,. di-methyl ethyl benzene tetramethyl benzene;

penta methyl benzene; hexamethyl benzene, and like 'homlogues of benzene. Apresently. preferred commercially available hydrocarbon (solvent.. naphtha) has the following characteristics:v

Flash point, not less than ffli; 8'7 Aniline point, lower than F -3Q Kauri-butanol value, higherthan'unmlu ASTM 13-88 distillation I Starting point F 278 Not morethan-lO percent at ?E. 286 Not less thanpercent at F 385 End point, not-highercthane- F 420i;

Suitable emulsifying agents for use inaccor dance with this invention arethose capable of forming substantially stable emulsions of j the aforementioned aromatic hydrocarbons in water. Cheap emulsifiers of this type include .sulfonated vegetable and petroleum oils such as. sulfonated castor oil, sulfonated coconut oil, 'sulfonated petroleum, and the like; the invention, however, is not to be construed as limited thereto.

In operation, the aromatichydrocarbon and the emulsifying agent are thoroughly mixedand the mixture is then forced under pressure through a spray nozzle having .very small orifices. which i is under the surfaceofithe water body in which the waterweeds to be eliminated aregrowing... Good mixing, high pressures (pressures as high] as 450 p. s. i. have beenused successfully), and. small nozzle openings all help. to increase fthe efiiciency of the treatments by causing better.di's pers-ion in the water, thus sending the emulsion further down stream. before it breaks; and.rises. to the surface. It is presently preferred tointroe duce between about ,p. .p. m.to- 300.1). ,p-. .m,, (parts of chemical per. million parts of waterinthe canal) to obtainsatisfactory weed control and maintain this concentrationfor about one hour in contact with the waterweeds. To main-., tain a concentration of p, p. m...for anlhour, 5 gallons ofthe chemical formulationmust be, applied to each. cubic foot per second o how I over, a period of one hour. I-I owever, it-is to be: noted that elimination -of waterwee ds 'is. possible with even lower concentration of the herbicidal agent; good kills have been obtained using .co centration as 1ow as about 12 5 pp. n.

The following examples willshowhow-theim;

vention may be carriedout but the invention is;

not limited thereto.

Example I A canal which :has a designedicapacity 'of 300 cubic zfeet per .secondiwas.so badly'infestedwith horned pondweed (Zannichellia pal ustrzs) that the maximum fiow had been reduced by 50 percent. Coal tar naphtha (boiling point range 275 to 406 F.) was thoroughly mixed with percent by volume of an emulsifying agent (equal parts of mahogany soap and sulfonated castor oil). This mixture was introduced into the canal beneath the surface at a pressure of pounds per square inch through a spray nozzle with a 0.22-inch opening. The concentration of chemical was maintained at 185 p. p. m. for minutes. The full carrying capacity of the canal was restored within 72 hours after this treatment, and the canal was free of submerged waterweeds for a distance of one mile below the point of application. Thus an extended length of flowing water course, i. e. a mile thereof, was effectively cleared of Weeds by the dispersal of the herbicidal mixture at the upstream end of such length at a rate maintaining a low concentration therein for a period of one hour. The turbulence accompanying the water flow, and the presence of the dispersing agent, was thus effective for maintaining the dispersion, carrying the herbicidal mixture forcibly against the weeds, and aiding its penetration of the weed tissues.

Example II A canal in which sago pondweed (Pctamogetcn pectz'natus) was the predominating species, but there were also scattered patches of horned pondweed and both species were in an advanced stage of maturity, was treated for one hour with 200 p. p. m. of a mixture of coal tar naphtha and 5 percent by volume of mahogany soap. Ninety percent of the leaves and stems of the saga pondweed had turned brown within 24 hours. Horned pondweed reacted more slowly but the final injury was about the same.

Thus it is apparent that a new simple and cheap method for the control of submersed waterweeds has been devised.

While the examples are confined to the eradication of horn pondweed and sage pondweed, the

invention is not limited thereto. Similar tests have been made on other types of submersed waterweeds such as various species of Potamogeton, Zannichellia, Anacharis, Myriophyllum, Cerataphyllum, Ranunculus, and like submersed aquatic vegetation, and the method has been found to be equally efiective.

While the examples describe the herbicidal agent as mixtures of coal tar naphtha and an emulsifier, many similar aromatic hydrocarbons and other emulsifiers have been tested and found to be as effective as the specific compositions described; however, economics of the problem place the described compositions in a preferred position at the present time.

While the present invention relates to the control and eradication of submersed waterweeds, a concurrent result is snail control. Although snail control is of minor importance in the United States, it is a problem of no little significance to other countries. Egypt is vitally concerned because many species of snails serve as hosts for such parasites, such as blood fiukes, liver fiukes, and the like. The disease caused by these parasites often reaches epidemic proportion along the Nile River. Snails feed on waterweeds; therefore, control of their food supply should reduce the snail population. Actually, the snails in the streams and canals in this country have been found tobe directly affected (killed) by this com- 4 position; so too have mosquito larvae, cray-fish, and fish. W

These compositions of this invention are volatile enough so that in a short time after the emulsion breaks they evaporate and are dissipated into the atmosphere, thereby minimizing any possible toxicity. While the normal concentrations used for waterweed control are not toxic to crop plants nor to animals which might drink the treated water, precautions should be taken to prevent the full concentration reaching such plants or animals. Care should be taken in their use due to the infiammability of the naptha. Breathing naphtha fumes and prolonged contacts of the bare skin with the composition should be avoided.

Since many widely differing embodiments of the invention will occur to one skilled in the art, the invention is not limited to the specific details illustrated or described, and various changes can be made therein without departing from the spirit and scope thereof. 7

What is claimed is:

The method of killing submerged waterweeds in an extended length of a flowing watercourse that comprises forming a mixture of surface active dispersing agent with a volatile herbicidal hydrocarbon having a boiling range lying between 250 and 400 degrees Fahrenheit, dispersing said mixture into the upstream regionv of the length of watercourse to be treated by submersed atomization under high pressure at a rate producing therein a concentration of from to 300 parts of herbicidal mixture per million parts of water, allowing the flow of the watercourse to carry the dispersed mixture downstream into contact with the waterweeds throughout the extended length of stream being treated while continuing the dispersing of mixture at the upstream end thereof for a period of the order of one hour, the flow of the water and the presence of the surface active dispersing agent maintaining the herbicidal hydrocarbon dispersed throughout the depth of the watercourse during its passage down the extended length of watercourse being treated, the fiow of the water carrying the dispersed herbicidal hydrocarbon into forcible contact with the waterweeds, and the dispersing agent aiding in the penetration of the herbicidal hydrocarbon into the waterweed tissues, whereby effective killing of the waterweeds is obtained.

JOHN M. SHAW. THOMAS R. BARTLEY. RICHARD S. ROSENIFELS.

REFERENCES CITED 1 The following references are of record in the file of this patent:

UNITEDVSTATES PATENTS 7 OTHER REFERENCES Water Works and Sewerage, May 1940, p. 231.

Bull. #V-33, Dept. Vegetable Crops, N. Y.

State College of Agriculture (April 1945), p. 3."

Chemical Weed Killers by Talbot, Div. of

Botany, Bureau of Plant Industry, U. S. Dept. of 7 Agriculture .(1931), p. 6.

Volck ayi 1937 Water Works and Sewerage, July 1938, pp. 688 

